Abstract

Radio frequency identification (RFID) is an automatic identification technology employing radio waves for detecting objects [1, 2]. Nowadays, RFID is widely used in many areas including asset tracking and real-time supply chain management. RFID relies on storing and retrieving information. The radiated wave energizes the IC chip to allow proper communication of data transfer between the RFID reader and the tag. Reader antenna is required to be low in profile yet provides wideband and high directivity characteristics in transmitting and receiving signal for data communication. In general, there are four frequency bands: low-frequency (LF) band (125 kHz), high-frequency (HF) band (13.56 MHz), ultra high-frequency (UHF) band (869, 915, and 950 MHz) and microwave band (2.45 and 5.8 GHz) [3]. The UHF and microwave bands are widely used due to their advantages of long read range and high data rate, it is desirable to design a single antenna which operates on both frequency bands.